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					               2003330
               Nokia BSC S10.5 ED, Vers. 2, Product
               Documentation
               Frequency Hopping




dn9814117      # Nokia Corporation                    1 (43)
Issue 6-1 en   Nokia Proprietary and Confidential
                                                                                      Frequency Hopping




         The information in this documentation is subject to change without notice and describes only the
         product defined in the introduction of this documentation. This documentation is intended for the
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         The information or statements given in this documentation concerning the suitability, capacity, or
         performance of the mentioned hardware or software products cannot be considered binding but
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         adequate and free of material errors and omissions. Nokia will, if necessary, explain issues
         which may not be covered by the documentation.
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         errors. NOKIA WILL NOT BE RESPONSIBLE IN ANY EVENT FOR ERRORS IN THIS
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         Copyright © Nokia Corporation 2003. All rights reserved.




2 (43)   # Nokia Corporation                                                                   dn9814117
         Nokia Proprietary and Confidential                                                  Issue 6-1 en
                                                                               Contents




Contents


                Contents 3

                List of tables 4

                List of figures 5

                Summary of changes 7

          1     Internal Description of Frequency Hopping 9
          1.1   Properties of frequency hopping 9
          1.2   Parameters of frequency hopping 15
          1.3   Restrictions to frequency hopping 16
          1.4   User interface of frequency hopping 16

          2     Frequency Hopping Implementation Description 19
          2.1   Fault Management of Frequency Hopping/recovery examples   21

          3     Implementation principles of Frequency Hopping, functional split 25
          3.1   BTS Implementation of Frequency Hopping 27
          3.2   BSC Implementation of Frequency Hopping 37

          4     Interaction of Frequency Hopping with Other Features 41




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List of tables


         Table 1.   Maximum BTS configurations supporting frequency hopping.   25




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                                                                                                 List of figures




List of figures


          Figure 1.    A call hopping over 4 frequencies.                  10
          Figure 2.    A 4 TRX BTS using baseband hopping.                      12
          Figure 3.    A 3-TRX BTS using RF hopping.                   13
          Figure 4.    Hopping groups in BB and RF hopping segments                   14
          Figure 5.    Example of baseband hopping.               20
          Figure 6.    Example of RF hopping.               21
          Figure 7.    Initial configuration of baseband hopping BTS.                22
          Figure 8.    MSs handled by TRXs 1, 3, and 4 can hop over all 4 frequencies.                    23
          Figure 9.    TRX 1 is blocked and does not carry traffic nor participate in hopping. 24
          Figure 10. Initial configuration of RF hopping BTS.                   24
          Figure 11.   TRX-2 is blocked out of use.              24
          Figure 12. Functional units for frequency hopping in 2nd gen. BTS.                27
          Figure 13. Loading switch settings.               28
          Figure 14. Data flow in the diversity case.             28
          Figure 15. Data flow in the redundant case.                 29
          Figure 16. Two TRXs using baseband hopping and the cyclic algorithm.                     30
          Figure 17. Dummy burst generation logic.                31
          Figure 18. Baseband hopping implementation in Talk-family BTS.                   32
          Figure 19. BB-hopping definition in the BSC.                 33
          Figure 20. Example of changing frequencies during pseudo BB-hopping                      34
          Figure 21. MetroSite Hopping environment                    35
          Figure 22. Relations between logical radio network objects.                 38




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                                              Frequency Hopping




6 (43)   # Nokia Corporation                          dn9814117
         Nokia Proprietary and Confidential         Issue 6-1 en
                                                                              Summary of changes




Summary of changes


Summary of changes

                  Changes between document issues are cumulative. Therefore, the latest document
                  issue contains all changes made to previous issues.

Changes made between issues 6 and 6V

                  Information on Nokia ConnectSite 10 and Nokia ConnectSite 100 base stations
                  has been added.

Changes made between issues 6 and 5

                  Changes due to feature enhancements

                  References to particular frequency bands have been removed from the chapter
                  Interaction of Frequency Hopping with Other Features , section Multi BCF and
                  Common BCCH Control .

                  Emphasised that the Packet Broadcast Control Channel (PBCCH) can use
                  Baseband hopping.

                  Other changes

                  Some changes to the layout.

Changes made between issues 5 and 4

                  Changes due to feature enhancements

                  Changes related to the BSS10 release made.

Changes made between issues 4 and 3

                  Changes due to feature enhancements

                  Added MetroSite BTS.




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                                              Frequency Hopping




8 (43)   # Nokia Corporation                          dn9814117
         Nokia Proprietary and Confidential         Issue 6-1 en
                                                               Internal Description of Frequency Hopping




1              Internal Description of Frequency
               Hopping
                  The radio interface of the GSM uses slow frequency hopping. Frequency hopping
                  consists of changing the frequency used by a channel at regular intervals.

                  This document describes the implementation of frequency hopping in Nokia's
                  GSM Base Station Subsystem (BSS). Neither the theory behind frequency
                  hopping nor radio network planning with associated capacity calculations are
                  discussed here.

                  More information about Frequency Hopping:

                  Frequency Hopping Implementation Description

                  Implementation principles of Frequency Hopping, functional split

                  Interaction of Frequency Hopping with Other Features

                  Internal Description of Frequency Hopping:



1.1            Properties of frequency hopping
                  Frequency Hopping (FH), or more accurately Slow Frequency Hopping (SFH), is
                  a feature designed to the GSM to increase quality and capacity in an urban
                  propagation environment. This is achieved by means of frequency diversity and
                  interference diversity.

                  Slow Frequency Hopping in the GSM means that the frequency of a radio time
                  slot (RTSL) is changing burst by burst. The frequency remains the same during a
                  burst (0,577 ms). All dedicated channel types and their associated channel types
                  (TCH /SACCH /FACCH , SDCCH/SACCH ) can hop. The Packet Broadcast
                  Control Channel (PBCCH ) can also hop (Baseband hopping).




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                                                                          Frequency Hopping




            frequency




                                                                                   time



          Figure 1.      A call hopping over 4 frequencies.


          The exact frequency on a certain moment of time is defined as a function of
          frequency hopping parameters related to a cell and a logical Radio interface
          channel (CA, MA, MAIO , HSN) and the Radio interface absolute frame
          number (see GSM 05 series). The frame number synchronises MS and BTS
          operation on a time basis.

          There are two main options for the implementation of frequency hopping;
          Baseband Hopping and Radio Frequency Hopping. Both of these are supported
          by Nokia's BSS. If the transceivers of the BTS are of the hopping synthesiser type
          (Nokia Talk family of base stations, Nokia PrimeSite, Nokia MetroSite, Nokia
          UltraSite, Nokia ConnectSite 10 or Nokia ConnectSite 100), you can choose the
          frequency hopping mode between non-hopping, RF hopping, and BB hopping.
          However, if Nokia PrimeSite has a BTS software package of DF6.0 or newer, it
          does not support frequency hopping. If the transceivers are of the conventional
          type (Nokia 2nd generation base stations), only non-hopping or BB hopping are
          possible. Nokia InSite does not support frequency hopping.

          The implementation level described here is BSS10.5. It consists of the following
          SW -builds: BSC S10.5, BTS DF6.0, BTS B13.0, BTS CX3.0/BTS CX3.1, BTS
          CXM3, BTS I2, BTS MV1.0 and BTS MVM1.0.

          Baseband hopping management

          There are two different hopping groups used with baseband hopping in each BTS.
          When the Intelligent Frequency Hopping (IFH) feature is used, an additional
          hopping group 3 is in use. See section Intelligent Frequency Hopping for more
          information on IFH and hopping on layer basis. For more information, refer to
          Intelligent Underlay-Overlay . Nokia InSite does not support frequency hopping.




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                                                           Internal Description of Frequency Hopping




               Group 1

               All radio time slots (RTSL-0), except the BCCH time slot, on the BTS belong to
               Group 1. It is managed through FHS-1 in the BSC's database. Hopping Sequence
               Number 1 (HSN1) is related to this group.

               Group 2

               All radio time slots (RTSL-1 to 7) on the BTS belong to Group 2. It is managed
               through FHS-2 in the BSC's database. HSN2 is related to this group.

               If baseband hopping is used on the BTS, all radio time slots belonging to the BTS
               are defined as hopping. The only exception to this is the BCCH time slot, which
               is always defined as non-hopping. In case there are dedicated signalling channels
               (SDCCH, CBCH ) on the BCCH time slot, they do not hop either.

               These hopping groups are maintained by adding and removing the Absolute
               Radio Frequency Channel Numbers (ARFCN) of the TRXs used in frequency
               hopping in the BTS. Based on the available ARFCNs in the BTS, the following
               hopping parameters, stored in the BSS Radio Network Configuration Database
               (BSDATA), are updated:

               .
                      Mobile Allocation (MA)
               .      Mobile Allocation Index Offset (MAIO)

               The ARFCN of a TRX is always removed from the hopping systems when the
               user sets the TRX to the administrative state LOCKED. The ARFCN is also
               removed from hopping if the system takes the TRX out of operational use due to
               a Carrier Unit (CU) or Transceiver Unit fault in the BTS. These operations cause
               clearing of calls in a BB hopping cell.

               The frequency hopping systems are configured and the parameters are implicitly
               defined by radio network configuration management in the BSC, when a BTS is
               created. For more information on radio network configuration management, refer
               to Radio Network Configuration Management. Through the BSC MMI, you can
               define whether the BTS uses frequency hopping or not. If baseband hopping is
               used in the BTS, you have to give a hopping sequence number (HSN) for all the
               hopping groups in the BTS.

               If baseband hopping is used in the BTS, the modification of the administrative
               state or the ARFCN of a TRX, and the creation or deletion of a TRX is possible
               only when a BTS has first been set in the administrative state LOCKED.

               Figure A 4 TRX BTS using baseband hopping shows an example of a 4-TRX
               BTS using baseband hopping:




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RTSL      0   1       2   3    4      5   6       7
TRX-1     B                                           f1B = BCCH timeslot. It does not hop.
                  0   0   0    0    0     0   0

TRX-2             1   1   1    1    1     1   1       f2    Time slots 1...7 of all TRXs
          0
                                                            hop over MA(f1,f2,f3,f4).
TRX-3     1       2   2   2    2    2     2   2       f3    This hopping group uses HSN-2.

TRX-4     2       3   3   3    3    3     3   3       f4    MAIOs have to be different between
                                                            same RTSLs in same hopping group.
   Time slot 0 of TRX-2,-3,-4 hop over MA(f2,f3,f4).
   This hopping group uses HSN-1.




                          Figure 2.       A 4 TRX BTS using baseband hopping.


                          RF hopping management

                          RF hopping can be used when the transceivers of the BTS are of the hopping
                          synthesiser type (Nokia Talk family of base stations, Nokia PrimeSite, Nokia
                          MetroSite, Nokia UltraSite, Nokia ConnectSite 10 or Nokia ConnectSite 100).
                          Then you can choose the frequency hopping mode between non-hopping, RF
                          hopping, and BB hopping. When the transceivers of the BTS are of the
                          conventional type (Nokia 2nd generation base stations), only non-hopping or BB
                          hopping are possible. Nokia InSite does not support frequency hopping. Also, if
                          Nokia PrimeSite has a BTS software package of DF6.0 or newer, it does not
                          support frequency hopping.

                          The Intelligent Frequency Hopping (IFH) feature introduces an additional
                          hopping group. See section Intelligent Frequency Hopping for more information
                          on IFH and hopping on layer basis. For more information, refer to Intelligent
                          Underlay-Overlay.

                          The frequencies for a hopping cell are defined by attaching the cell to one of the
                          mobile allocation frequency lists (MA-lists) defined by the operator. The system
                          calculates the MAIOs, and the operator gives the HSN for the cell. The BCCH
                          transceiver cannot hop, but it transmits a continuous BCCH frequency. Note that
                          the MA used must contain at least as many frequencies as there are unlocked
                          hopping transceivers in the BTS. The MA or the HSN can be changed only when
                          the hopping cell is locked.

                          You can create up to 255 mobile allocation frequency lists (MA-lists) and use
                          them freely with different cells. One list can contain up to 63 frequencies.




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                                                                           Internal Description of Frequency Hopping




                           Changes in the transceiver configuration of an RF hopping cell affect only the
                           transceiver that is being handled, other transceivers are not disturbed. The
                           hopping mode can be changed when the BTS is locked. Nokia Talk family of
                           base stations require that, in addition to the BTS being locked, the changes
                           between hopping modes are done via changing the hopping mode first to non-
                           hopping mode. If an alarm is received from the BCF indicating a fault that has an
                           effect on frequency hopping, the BSC blocks the faulty object.

                           Figure A 3-TRX BTS using RF hopping shows an example of a 3-TRX BTS
                           using RF hopping. Note that only one mobile allocation frequency list can be
                           attached to the BTS at a time.


   TRX-1       B                                      fa B = BCCH timeslot. TRX does not hop.

   TRX-2       0   0   0       0   0   0    0  (fb) Non-BCCH TRXs are hopping over
                                                 0
                                                    the MA-list (f1,f2,f3,...,fn) attached to the cell.
   TRX-3 1      1    1   1    1  1     1  1    (fc)
                                                    MAIOs have to be different between
                                                    same RTSLs in same hopping group.
 Only one hopping group. Only HSN-1 is meaningful.




                           Figure 3.       A 3-TRX BTS using RF hopping.


                           Freeform RF Hopping

                           Adjacent frequencies cannot be used in the mobile allocation frequency list since
                           it would cause adjacent channel interference within the cell and also between the
                           cells in the same BTS site. However, in order to fully benefit from the very tight
                           reuse factor and fractional loading in the hopping network offered by the use of
                           RF hopping, the operator needs means to share the same frequency sets between
                           adjacent sectors of a BTS site. At the same time channel collisions and adjacent
                           channel interference have to be avoided. Thus the operator needs to be able to
                           define all the frequency hopping parameters, including MAIOs.

                           The operator is provided with two parameters for MAIO manipulation to use RF
                           hopping more flexibly and more efficiently:

                           .       User defined parameter to set the starting point for allocation of the MAIOs
                                   per cell, i.e., the lowest MAIO in a cell can be bigger than zero.
                           .       User defined parameter to allow discontinuous MAIO numbering to be
                                   used in a cell, for example, MAIOs 0,2,4,6.




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                           Hopping management with common BCCH


      BB hopping
      PGSM 900 BTS,                         EGSM 900 BTS,                       GSM 1800 BTS,
      two hopping groups                    two hopping groups                  two hopping groups

  0    1   2   3   4   5    6   7       0     1   2   3   4     5   6   7   0    1   2   3   4   5    6   7

  0    1   2   3   4   5    6   7       0     1   2   3   4     5   6   7   0    1   2   3   4   5    6   7

  0    1   2   3   4   5    6   7                                           0    1   2   3   4   5    6   7


      RF hopping
      PGSM 900 BTS,                         EGSM 900 BTS,                       GSM 1800 BTS,
      one hopping group                     one hopping group                   one hopping group

  0    1   2   3   4   5    6   7       0     1   2   3   4     5   6   7   0    1   2   3   4   5    6   7

  0    1   2   3   4   5    6   7       0     1   2   3   4     5   6   7   0    1   2   3   4   5    6   7

  0    1   2   3   4   5    6   7                                           0    1   2   3   4   5    6   7




                           Figure 4.        Hopping groups in BB and RF hopping segments


                           The multiband network will support frequency hopping within each band of
                           operation. Frequency hopping between the bands of operation is not supported.

                           In the segment, the resources of different types are grouped as separate BTSs. All
                           the resource types have their own hopping parameters and hopping groups.
                           Figure Hopping groups in a segment gives an example of the different hopping
                           groups of a segment in the Common BCCH Control feature.

                           The segment architecture enables the network to have BTSs without a BCCH
                           TRX. This reduces the amount of hopping groups in the regular area of a BTS
                           due to no need for a separate group for the BCCH TRX in RF hopping. In the
                           case of BB hopping, TSL0 and other TSLs are separated and these are seen as
                           two different hopping groups.

                           Back to Internal Description of Frequency Hopping




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                                                                Internal Description of Frequency Hopping




1.2            Parameters of frequency hopping
                  The BCF type (TYPE) , the hopping mode of the cell (HOP/UHOP) ,
                  the Mobile Allocation Frequency Lists (MA) band and frequencies,
                  the identification number of the MA list attached to the cell
                  (MAL/UMAL) , the initial frequencies of the transceivers
                  (FREQ) , the cell based Hopping Sequence Numbers (HSN1, HSN2 and
                  UHSN) , MAIO Offset (MO/UMO) , and MAIO Step (MS/UMS) are defined
                  with the MML commands of the BSC or by Nokia NetAct through the Q3
                  interface.

                  On the Abis O&M interface, the hopping mode and the MA, MAIOs, and HSNs
                  are sent to the BCF when it is configured. If the BCF does not accept the
                  configuration and sends a negative acknowledgement, an alarm is set. Even so,
                  the data is stored in the BSC database until the user modifies it again.

                  With the MAIO Offset parameter you can set the lowest MAIO value per
                  sector to other than 0. This makes it is possible to use the same MA list for two or
                  more sectors in the site without collisions. However, because the sectors
                  controlled by one BCF operate in frame synchronisation, the HSN values must be
                  equal between the sectors in order to each frequency to be used only once during
                  one frame period. If the HSN values differ between the sectors, collisions will
                  occur regularly. Using the MAIO Offset parameter requires that the sectors
                  operate in frame synchronisation.

                  With the MAIO Step parameter you can use successive channel numbers within
                  a single cell. For example, with step value '2' 400kHz channel separation is
                  achieved.

                  When both MAIO Offset and MAIO Step parameters are used, even re-use 1/
                  1 is possible in a 3-sector BTS site, without any co-channel collisions or
                  detrimental interference from adjacent frequency channels. Note that you have to
                  make sure that the MA-list is long enough. For example, if you have a 3-sector
                  site, 4 TRXs in each, and you want to share a single MA-list between all of those
                  with 400 kHz minimum channel separation, you have to reserve at least 18
                  frequencies for the MA-list plus 3 BCCH frequencies, that is 21 frequencies
                  altogether.

                  Back to Internal Description of Frequency Hopping




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1.3       Restrictions to frequency hopping
             There are some restrictions concerning the cell allocation frequencies on the Abis
             and Radio interface messages of the GSM1800/GSM1900 system. The following
             allocation coding methods can be used: "variable bit map", "256 range" and "512
             range".

             Only one hopping mode (BB or RF) can be active on a BTS at a time, or if the
             site type is Nokia Talk-family, on a BCF at a time.

             Cyclic and random hopping are not allowed simultaneously on one Nokia 2nd
             generation base station site.

             A floating TRX cannot be used in BB hopping.

             The values of the Training Seqency Codes (TSCs) of all the TRXs of a BB
             hopping layer must be equal. If the BCCH/PBCCH TRX's frequency is used in a
             BB hopping layer, then the TSCs of all TRXs of that BB hopping layer must be
             the same as the BTS colour code (BCC).

             Back to Internal Description of Frequency Hopping



1.4       User interface of frequency hopping
             Creation of BB hopping BTS

             A Baseband Frequency Hopping BTS is created in a similar way to any BTS;

             1.     First the BCF is created. In this phase the BTS generation is given to the
                    system, some checks later on are based on this information (for example
                    RF hopping is not possible with Nokia 2nd generation base stations).
             2.     When the BTS is created, hopping related parameters of the BTS can be
                    set.
             3.     The rest of the parameters and procedures are similar to the
                    parameterization of a non-hopping BTS.




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                                                           Internal Description of Frequency Hopping




               4.     The hopping configuration parameters are transferred from the BSC to the
                      BTS site when the user unlocks the BTS. The BSC sends a configuration
                      message via the Abis O&M link to the BTS including CA, MA, MAIO ,
                      HSN, ARFCN , and hopping mode. The BCF (BTS-OMU) of the site then
                      re-formats the hopping related parameters and forwards them to the
                      hopping control units of the BTS (FQHU in Nokia 2nd generation base
                      stations, FHDSP in Nokia Talk family of base stations, and CHDSP in
                      Nokia PrimeSite, Nokia MetroSite, Nokia UltraSite, Nokia ConnectSite 10
                      and Nokia ConnectSite 100).
               5.     When the BTS is up and running, the hopping system is in place and
                      working even though no signal (except BCCH) is transferred. The call-
                      related hopping parameters (MA, MAIO etc.) over the Abis telecom
                      interface are not configuring the BTS any more, they go to the MSs.

               Creation of RF hopping BTS

               The creation of an RF hopping BTS has MA-handling as an extra step;

               1.     First the BCF is created. In this phase the BTS generation is given to the
                      system, some checks later on are based on this information (for example,
                      RF hopping is not possible with 2nd generation BTS).
               2.     Before RF hopping of the BTS can be fully defined, the MA-lists must be
                      defined at the BSC-level.
               3.     When the BTS is created, the hopping related parameters of the BTS can
                      be set. The BTS must also be attached to an MA-list.
               4.     See steps 3) , 4) and 5 ) in Creation of BB hopping BTS.

               Mobile Allocation Frequency List

               With the commands of the BCCH and Mobile Allocation Frequency List and RA
               Handling (BAZAAR) command group you can create, modify, remove, and
               display mobile allocation frequency list objects in the BSS Radio Network
               Configuration Database. For more information, refer to BCCH and Mobile
               Allocation Frequency List and RA Handling.

               With the commands of the Base Transceiver Station Handling command group
               (PBTHAN) you attach any of these lists to a BTS. For more information, refer to
               Base Transceiver Station Handling in BSC.




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          Creation of mobile allocation frequency list

          With the CREATE MOBILE ALLOCATION FREQUENCY LIST command you
          can create a mobile allocation frequency list in the BSS Radio Network
          Configuration database. The mobile allocation frequency list is identified by a
          number. The frequency band type of the mobile allocation frequency list is an
          obligatory parameter.

          Deletion of mobile allocation frequency list

          With the DELETE MOBILE ALLOCATION FREQUENCY LIST command you
          can remove a mobile allocation frequency list from the BSS Radio Network
          Configuration Database. The list identification has to be given as a parameter.
          You cannot remove the MA-list if it is still used by a BTS.

          Modifying mobile allocation frequency list

          With the MODIFY MOBILE ALLOCATION FREQUENCY LIST command
          you can add or remove frequencies to/from mobile allocation frequency lists.

          Interrogation of mobile allocation frequency list data

          With the OUTPUT MOBILE ALLOCATION FREQUENCY LIST command
          you can display the mobile allocation frequency list data stored in the BSS Radio
          Network Configuration database. The list identification can be given as a
          parameter. If the lists are used by some BTSs, the numbers of the related BTSs
          are printed out.

          If you do not identify the list, all the mobile allocation frequency lists are
          displayed.

          Interrogation of hopping parameters

          You can print out all user maintained hopping parameters with MML commands.

          With the OUTPUT BASE CONTROL FUNCTION command you can
          interrogate all BCF-wide hopping data - including data which is maintained by
          the system. You can also print out all cell-wide hopping data with the OUTPUT
          BASE TRANSCEIVER STATION DATA command.

          Back to Internal Description of Frequency Hopping




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                                                        Frequency Hopping Implementation Description




2              Frequency Hopping Implementation
               Description
                 When frequency hopping is used, the Basic Call procedure differs from the non-
                 hopping case only in the channel assignment phase.

                 The radio resource management program block (RRMPRB) in the BSC selects a
                 free logical dedicated channel in a hopping BTS in the same way as in the non-
                 hopping BTS.

                 The channel selection procedure is influenced by the idle channel interference
                 levels measured by the base station. In a hopping BTS the idle channel
                 interference measurements are done in all frequencies included in the Mobile
                 Allocation list.

                 If hopping is not used, the radio interface channel can be defined with ARFCN ,
                 Radio Time slot number and subchannel number. If hopping is used the ARFCN
                 is replaced with MA, MAIO and HSN. The MA determines which frequencies
                 from the Cell Allocation are used in the hopping sequence.

                 After the selection of a dedicated channel the BSC determines the required
                 MAIO, HSN and MA for the selected channel and sends them to the mobile
                 station in the IMMEDIATE_ASSIGNMENT or ASSIGNMENT message. The
                 MS reads the Cell Allocation from the System Information Messages which are
                 broadcast on the BCCH and, in the case of GPRS , from the Packet System
                 Information Meassages which are broadcast on the PBCCH . The base station has
                 received the used MA, MAIO and HSN in the BTS configuration phase via O&M
                 signalling link.

                 Example: Baseband Hopping

                 Four consecutive calls are made in a cell with four TRXs. Baseband hopping is
                 used in the cell. For all calls, the BSC allocates the RTSL-2 in different TRXs.
                 Figure Example of baseband hopping illustrates how the bursts are organised in
                 the air interface. In this case only RTSL-2 is observed.




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Call 1: TRX1, RTSL 2, MAIO = 0, MA(f1,f2,f3,f4), HSN = 0 (Cyclic Hopping)

  RTSL      0    1       2       3       4       5       6        7         Bursts in RTSL 2

  TRX 1    B     0   0       0       0       0       0       0     0   f1

  TRX 2     0    1   1       1       1       1       1       1     1   f2

  TRX 3     1    2   2       2       2       2       2       2     2   f3

  TRX 4     2    3   3       3       3       3       3       3     3   f4
                                                            2     2     2                      2   2   2   2   2   Time
Call 2: TRX2, RTSL 2, MAIO = 1, MA(f1,f2,f3,f4), HSN = 0 (Cyclic Hopping)

  RTSL      0    1       2       3       4       5       6        7         Bursts in RTSL 2

  TRX 1    B     0   0       0       0       0       0       0     0   f1

  TRX 2     0    1   1       1       1       1       1       1     1   f2

  TRX 3     1    2   2       2       2       2       2       2     2   f3

  TRX 4     2    3   3       3       3       3       3       3     3   f4
                                                            2     2     2                      2   2   2   2   2   Time
Call 3: TRX3, RTSL 2, MAIO = 2, MA(f1,f2,f3,f4), HSN = 0 (Cyclic Hopping)

  RTSL      0    1       2       3       4       5       6        7         Bursts in RTSL 2

  TRX 1    B     0   0       0       0       0       0       0     0   f1

  TRX 2     0    1   1       1       1       1       1       1     1   f2

  TRX 3     1    2   2       2       2       2       2       2     2   f3

  TRX 4     2    3   3       3       3       3       3       3     3   f4
                                                            2     2     2                      2   2   2   2   2   Time
Call 4: TRX4, RTSL 2, MAIO = 3, MA(f1,f2,f3,f4), HSN = 0 (Cyclic Hopping)

  RTSL      0    1       2       3       4       5       6        7         Bursts in RTSL 2

  TRX 1    B     0   0       0       0       0       0       0     0   f1

  TRX 2     0    1   1       1       1       1       1       1     1   f2

  TRX 3     1    2   2       2       2       2       2       2     2   f3




                                 Figure 5.                       Example of baseband hopping.


                                 Example: RF Hopping

                                 RF Hopping on TRX-2 in a two TRX cell. The first call is made on RTSL-2 of
                                 the non-hopping BCCH TRX and the second call is made on RTSL 2 ot the RF
                                 Hopping TRX. Figure Example of RF hopping illustrates how the bursts are
                                 organised in the air interface. In this case only RTSL-2 is observed.




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                  Call 1: TRX1, RTSL 2, ARFCN = f1

                    RTSL      0    1    2    3    4     5    6    7         Bursts in RTSL 2

                    TRX 1     B                                        f1

                    TRX 2     0   0     0    0    0     0    0    0    f2

                                                                       f3

                                                                       f4
                                                                             2     2    2      2   2   2   2   2   Time
                  Call 2: TRX2, RTSL 2, MAIO = 0, MA (f2,f3,f4), HSN = 0 (Cyclic Hopping)

                    RTSL      0    1    2    3    4     5    6    7         Bursts in RTSL 2

                    TRX 1     B                                        f1

                    TRX 2     0   0     0    0    0     0    0    0    f2

                                                                       f3

                                                                       f4
                                                                             2    2     2      2   2   2   2   2   Time




                  Figure 6.        Example of RF hopping.


                  More information about Frequency Hopping:

                  Internal Description of Frequency Hopping

                  Implementation principles of Frequency Hopping, functional split

                  Interaction of Frequency Hopping with Other Features

                  Fault Management:



2.1            Fault Management of Frequency Hopping/recovery
               examples
                  The following three examples show the recovery of a hopping BTS.




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                          TRX (FU) fault, baseband hopping BTS


  RTSL 0      1       2   3    4      5   6       7
TRX-1 B                                               f1B = BCCH timeslot. It does not hop.
                  0   0   0    0      0   0   0

TRX-2             1   1   1    1      1   1   1       f2       Time slots 1...7 of all TRXs
          0
                                                               hop over MA(f1,f2,f3,f4).
TRX-3                                                 f3       This hopping group uses HSN-2.
          1       2   2   2    2      2   2   2

TRX-4     2       3   3   3    3      3   3   3       f4       MAIOs have to be different between
                                                               same RTSLs in same hopping group.
   Time slot 0 of TRX-2,-3,-4 hop over MA(f2,f3,f4).
   This hopping group uses HSN-1.




                          Figure 7.       Initial configuration of baseband hopping BTS.


                          FU fault is the trigger in this example (Frame Unit (FU) and Carrier Unit (CU) are
                          functional parts of Nokia 2nd generation base stations). The fault can be internal
                          (for example a FU hardware) or external (for example losing a LAPD -link of the
                          TRX). This fault type and recovery mechanism is not applicable for later BTS
                          generations due to more integrated hardware.

                          1) The BTS alarms the BSC, or the BSC detects a non-functional LAPD. TRX-2
                          is suspected to be faulty.

                          2) The BSC clears all the calls which are allocated to those Abis circuits
                          corresponding to TRX-2. Calls on TRXs 1, 3 and 4 remain untouched.

                          3) The BSC blocks TRX-2 in order not to allow new traffic for Abis circuits
                          related to it.

                          In this fault type the BSC can assume that all the Carrier Units (CU) are
                          functioning properly, so the hopping parameters can be left untouched. MSs
                          handled by TRXs 1, 3, and 4 in this example can still hop over all 4 frequencies.




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                 RTSL 0         1       2   3       4   5   6       7
               TRX-1   B                                                f1
                                    0   0   0       0   0   0   0

                                    1   1   1       1   1   1   1       f2
                           0

               TRX-3       1        2   2   2       2   2   2   2       f3

               TRX-4       2        3   3   3       3   3   3   3       f4




               Figure 8.       MSs handled by TRXs 1, 3, and 4 can hop over all 4 frequencies.


               TRX (CU) fault, baseband hopping BTS

               Initial configuration: as in Figure Initial configuration of baseband hopping BTS .

               The fault in this example is on the BCCH Carrier Unit. The fault is such that the
               CU of TRX-1 (Nokia 2nd generation base stations) or the Transceiver Unit of
               TRX-1 (Nokia Talk-family of base stations) does not work anymore.

               1.     The BTS alarms the BSC. TRX-1 is suspected to be faulty.
               2.     The BSC blocks all the TRXs of the cell for a while. This causes clearing
                      of all ongoing calls of the cell.
                      Frequency redefinition procedure is not used because:
                      .        in fault cases operation should be as straightforward as possible, no
                               complex procedures should be triggered
                      .        it is not certain, especially in case of smaller configurations, that any
                               messages can be carried over the Radio interface reliably once one
                               frequency (or more) is missing from a hopping group
                      .
                               it is not certain whether the MSs would still use the BTS concerned
                               at the time of frequency redefinition.
               3.     The BSC calculates new hopping parameters.
               4.     The BSC deblocks TRXs 2, 3 and 4. New hopping and TRX parameters
                      are transferred to the BTS. TRX-2 is restarted with BCCH on RTSL-0 , and
                      hopping is reconfigured.
               5.     The BSC allows new traffic for TRXs 2, 3 and 4.




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  RTSL 0      1       2   3      4      5           6           7
TRX-1                                                                    f2                Frequencies are swapped. TRX-1 is
                                                                                           locked and does not carry traffic.
TRX-2     B       0   0   0      0      0       0           0            f1

TRX-3     0       1   1   1      1      1       1           1            f3

TRX-4     1   2       2   2     2      2        2           2            f4




                          Figure 9.              TRX 1 is blocked and does not carry traffic nor participate in
                                                hopping.


                          TRX fault, RF hopping BTS


TRX-1     B                                                              faB = BCCH timeslot. TRX does not hop.

TRX-2     0   0       0   0      0      0       0               0       (fb)       Non-BCCH TRX is hopping over
                                                                                   the MA-list (f1,f2,f3) attached to the cell.




  Only one hopping group. Only HSN-1 is meaningful.




                          Figure 10.                Initial configuration of RF hopping BTS.


                          1.          The BTS alarms the BSC, or the BSC detects a non-functional LAPD.
                                      TRX-2 is suspected to be faulty.
                          2.          The BSC clears all the calls which are allocated to those Abis circuits
                                      corresponding to TRX-2. Calls on TRX-1 remain untouched.
                          3.          The BSC blocks TRX-2 in order not to allow new traffic for Abis circuits
                                      related to it.


                              TRX-1         B

                              TRX-2         -           -           -          -       -     -     -     -



                          Figure 11.                TRX-2 is blocked out of use.




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                                                 Implementation principles of Frequency Hopping, functional split




                    Back to Frequency Hopping Implementation Description




3                Implementation principles of Frequency
                 Hopping, functional split
                    In the GSM system the BSS is responsible for implementing frequency hopping.
                    The MSC is not involved in it. The only indirect MSC impact in hopping is that
                    some MSC-transparent A interface messages (handover command information
                    coming from the target BSC) are longer than in the non-hopping case.

                    Nokia NetAct is involved in managing the BTS and hopping parameters. They
                    are managed from Nokia NetAct like other cell parameters. Fault management
                    from Nokia NetAct's point of view has no special functions related to frequency
                    hopping. Alarms from a hopping BTS are handled like alarms from a non-
                    hopping BTSs.

                    The maximum BTS configurations supporting hopping are listed in Table
                    Maximum BTS configurations supporting frequency hopping .



                   Table 1.       Maximum BTS configurations supporting frequency
                                 hopping.

BTS type               Baseband Hopping            Note       RF Hopping               note

                                                                                        

2nd generation                                                                          

    Omni               10 TRXs                                       -

    Sectorised         4+4+4 TRXs                                    -                  

Talk-family                                                                             

    Omni               12 TRXs                                12 TRXs

    Sectorised         4+4+4 TRXs                             4+4+4 TRXs                

PrimeSite                                                                               




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                         Table 1.       Maximum BTS configurations supporting frequency
                                       hopping. (cont.)

BTS type                     Baseband Hopping            Note     RF Hopping              note

  Omni                       16 TRXs                              16 TRXs                  

 Sectorised                  n*y TRXs                    1)       n*y TRXs                1)

MetroSite, ConnectSite                                                                     
10

 Omni                        4 TRXs                      2)       4 TRXs                   

 Sectorised                  2+2 TRXs                    2)       2+2 TRXs                 

UltraSite, ConnectSite
100

 Omni                        12 TRXs                              12 TRXs

 Sectorised                                              3)                               3)

1) The amount of sectors is not limited, even each TRX can be a sector of its own. A maximum of 16
TRXs per BCF is allowed, and these can then be freely divided into sectors of different sizes. The
only rule is that n*y must be less than or equal to 16.
2) C1.0 SW supports only RF-hopping. C2.0 BB-hopping is pseudo-BB hopping. The same hopping
group of the cell cannot include both normal TRXs and high-power TRXs.
3) UltraSite limitations for sector configuration are: a maximum of 12 TRXs / sector and a maximum
of 6 sectors / cabinet. Thus the possible sector configurations go from 2+2+2+2+2+2 TRXs to 6+6
TRXs.


                          More information about Frequency Hopping:

                          Internal Description of Frequency Hopping

                          Frequency Hopping Implementation Description

                          Interaction of Frequency Hopping with Other Features

                          Implementation principles:




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3.1            BTS Implementation of Frequency Hopping
                  2nd generation implementation (DE21/DF12/DG26)

                  The Nokia 2nd generation base stations' implementation is baseband hopping
                  only. RF hopping is not supported now nor in the future. All carrier units have
                  fixed frequencies.

                  The hopping function is realised by multiplexing baseband digital bit streams
                  between Frame Unit and Carrier Units. Physically, these bit streams are carried
                  over a 10 Mbit/s serial two-way link (FHI-link, Frequency Hopping Interface
                  link). All links are fed through a special Frequency Hopping Unit (FQHU) that
                  takes care of the actual multiplexing and hopping law calculation. Figure
                  Functional units for frequency hopping in 2nd gen. BTS clarifies the set-up.


                       FU1                                   FU1



                       FU2                 F                 FU2
                                           Q
                                           H
                                           U
                       FU3                                   FU3




                      FU12                                 CU12




                  Figure 12.     Functional units for frequency hopping in 2nd gen. BTS.


                  The FQHU itself is basically a multiplexing device capable of multiplexing 12
                  simultaneous serial links. FQHU has two processors, one general purpose
                  processor for Q1-bus interface and housekeeping functions and one DSP
                  dedicated for frequency hopping algorithm calculation. The switching matrix is a
                  passive device into which the DSP loads (with the assistance of FIFO &
                  associated clocking circuitry) required switch settings twice during a time slot.
                  The first load is used to control data transfer from FU to CU, second load is for
                  the CU->FU transfer. Figure Loading switch settings illustrates this further.




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                 Load new switching
                 matrix settings




                       Guard period            Rx data transfer    Guard period
                                               (CU -> FU)
                     Tx data transfer
                     (FU -> CU)

                         one timeslot duration (0.577 ms)



          Figure 13.     Loading switch settings.


          The hopping unit is common for a BTS site, the sectors of a BTS use the same
          hopping unit. The data transmitted between FU and CU is digital, in downlink
          direction the modulating bits are transmitted to CU for actual modulation,
          upconversion and power amplification. In uplink direction the data consists of
          digital samples of the baseband I- and Q-signals.

          The FHI-link can be duplicated for reliability or because of diversity. If diversity
          is not used, the other link will act as a hot redundancy, which means that it is
          immediately and automatically taken into use if the primary link fails. When
          diversity reception is used, the other link is used for carrying the signal from the
          diversity receiver. When two links are employed, a second FQHU is also
          required. Figures Data flow in the diversity case and Data flow in the redundant
          case explain this set-up further.



                                      FQHU                        Tx
                                      primary


                FU
                                                                  Rx
                                     FQHU
                                     diversity
                                                                  RxD



          Figure 14.     Data flow in the diversity case.




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               Figure Data flow in the diversity case shows the logical flow of data and does not
               represent a physical link structure. On downlink the redundancy continues. The
               same data is transmitted through both links. On uplink one link carries data from
               the primary receiver and another carries data from the diversity receiver.


                                                                          Tx
                                          FQHU
                                          primary

                    FU


                                          FQHU
                                          diversity
                                                                         Rx




               Figure 15.     Data flow in the redundant case.


               When redundancy is used the same data is transmitted through both links.

               FQHU is capable of supporting a maximum of 15 hopping groups at a time. This
               is sufficient as in a three sector IFH configuration the number of hopping groups
               used is 12. Both random and cyclic hopping modes are supported but not
               simultaneously. This means that the whole site (= all sectors) must be using either
               cyclic hopping or random hopping. With random hopping the HSN can be
               selected freely. Then all hopping groups can have a different HSN at the same
               time. The number of CUs must equal the number of FUs, the maximum number
               of TRXs supported is 12.

               The specification requires that transmission and modulation on the BCCH is
               continuous and no power control takes place for dedicated channels located on
               the BCCH carrier. This is ensured in the following way.

               In the serial data from FU to CU there is control information for transmit power
               level, the transmitter on/off bit and the BCCH-bit. The DSP processing a BCCH
               time slot sets the BCCH-info bit and also includes the BCCH power level. The
               carrier unit that receives a data burst where the BCCH-bit is set forces the
               transmitter to operate on the power level indicated in the burst for 8 consecutive
               time slots. Power level information and the power on/off-bit are ignored during
               those 8 time slots thus ensuring that the power level set for the BCCH is
               maintained constantly.




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                                All FUs generate constantly valid transmit bursts towards CU. If a channel is
                                active, these bursts contain traffic data, such as speech or signalling. When a
                                channel is idle the FUs keep on generating dummy bursts but the transmitter on/
                                off bit is set to off-position. Due to baseband hopping, these bursts are directed to
                                all CUs in turn. When this burst is directed to a CU transmitting the BCCH, this
                                bit (and the power level) is ignored and the data bits are used to modulate the
                                carrier.

                                In the following example there are two TRXs using baseband hopping and the
                                cyclic algorithm. The BCCH time slot is not hopping, thus TSL-0 of the TCH-
                                TRX cannot hop either. The remaining time slots 1-7 are hopping. The resulting
                                data stream is transmitted next to the CUs. The BCCH time slot ensures that
                                power remains constant in every time slot. When no calls are active, a dummy
                                burst is transmitted in idle time slots, here denoted with `I' and `i'. On the BCCH,
                                the transmitter is active all the time since the BCCH time slot is repeated in every
                                eighth time slot. On the TCH carrier, transmission takes place only when data of
                                an active call is routed through it. In the following example the transmitter is
                                active in time slots 6 and 4 on even and odd frames, respectively.

ts:    0    1   2   3   4   5     6       7
       B    I   I   I C1 I        I       I    even numbered frames               odd numbered frames
                                              B I I I C1 I I I                B    i i i i i C2 i
           BCCH-FU
                                      F           CU1               BCCH-carrier
                                      Q
                                      H
                                      U
                                                  CU2               TCH carrier
           TCH-FU
                                              i    i    i   i   i   i C2 i    i    i   i   i C1   i   i   i
 ts:   0    1   2   3   4   5 6 7
       i    i   i   i   i   i C2 i




                                Figure 16.        Two TRXs using baseband hopping and the cyclic algorithm.


                                For FU failure cases the FQHU also has a dummy burst generation logic, which
                                makes it possible to replace the signal from a FU with an FQHU-generated
                                dummy burst. This is necessary after a FU failure when the FU itself cannot
                                generate these bursts. The OMU controls this feature, whenever it detects a
                                situation where a FU is incapable of producing a dummy burst for idle channels,
                                it commands the FQHU to fill in for this FU. When the FU is back in service, the
                                fill-in is discontinued. The dummy burst generation logic is common to all FUs,
                                and one or all FUs can be replaced simultaneously. Figure Dummy burst
                                generation logic explains this further.




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                                        Dummy
                                         burst
                                       generation
                                         logic




               FU1
                                                                                                  FU1

               FU2                                                                                FU2

                                                                  Switching                       FU3
               FU3
                                                                    matrix




                                                                                                  FU12
               FU12




               Figure 17.     Dummy burst generation logic.


               The timing of sectors is derived from a common clock unit (MCLP), so the
               different sectors are bit-synchronised thus enabling the use of synchronous
               handovers. Consequently, the hopping sequences are synchronised too.

               Nokia Talk-family of base stations (DE34/DF34/DG35) and Nokia PrimeSite
               implementation

               In Nokia Talk-family of base stations and Nokia PrimeSite implementation, both
               baseband hopping and RF hopping are implemented. In Nokia PrimeSite the
               baseband hopping is not relevant as the package only contains one TRX, and thus
               the baseband bit streams cannot be multiplexed between fixed frequency
               transmitters. Therefore, in Nokia PrimeSite technically speaking only RF hopping
               is implemented. However, if Nokia PrimeSite has a BTS software package of
               DF6.0 or newer, it does not support frequency hopping.

               Baseband hopping implementation is slightly different in Nokia Talk-family of
               base stations than in Nokia 2nd generation base stations. The principle is the
               same, but the division of functionality is different because of the different
               architecture. Functionality inside one TRX is divided between burst level
               operations (EQDSP) and block level operations (CHDSP). Burst level operations
               cover all operations done for a single burst transmitted and received, such as




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          ciphering/deciphering, equalisation, bit detection, and diversity combining for
          example. Block level operations deal with blocks of information, such as a speech
          block or a signalling block. These operations cover for example interleaving/de-
          interleaving, block coding/decoding. The baseband hopping interface resides
          between this logical division.



                                          FHDSP



               TRX1,                                         TRX1,
               CHDSP                                         EQDSP

               TRX2,                                         TRX2,
               CHDSP                                         EQDSP
                                               F
                                               B
               TRX3,                           U             TRX3,
               CHDSP                           S             EQDSP



               TRX12,                                        TRX12,
               CHDSP                                         EQDSP




          Figure 18.     Baseband hopping implementation in Talk-family BTS.


          FHDSP is a digital signal processor (DSP) dedicated to controlling the frequency
          hopping operation. In baseband hopping the FHDSP controls the information
          transfer between the EQDSP and the CHDSP thus realising the hopping. The
          FBUS is a two-way parallel bus dedicated for this purpose and dimensioned to
          support a maximum of 12 TRXs.

          With RF hopping, the bus is also used but connections are always made one-to-
          one, that is the EQDSP of TRX-1 is always connected to the CHDSP of TRX-1.
          The FBUS is then used for sending the RF channel number from the FHDSP to
          be used on the next time slot. Two synthesiser banks are used; while one is in use
          the other is being tuned to the frequency used in the next time slot. Delivery of
          channel numbers from FBUS to synthesisers is done by the hardware.

          In Nokia PrimeSite the operation is logically the same as in Nokia Talk-family of
          base stations, but the FBUS is physically missing and functions of the FHDSP are
          integrated to the CHDSP.




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                         RF hopping and BB hopping cannot be used simultaneously. This means that all
                         sectors must use the same hopping mode, if any. However, some sectors may be
                         hopping while others are not. Other configuration options restrict the use of the
                         hopping mode too, namely the cavity combiner prevents the use of RF hopping.
                         To use cavity combiners, transmitters must have fixed frequencies and therefore
                         only baseband hopping is enabled.

                         Nokia MetroSite and ConnectSite 10 implementation

                         The Nokia MetroSite BTS SW release 1.0 supports RF-hopping.

                         As of release CX2.0, also BB-hopping is supported. The actual implementation
                         of the BB-hopping is so called 'pseudo-BB' hopping. From the BSC point of
                         view, pseudo BB-hopping is defined as BB-hopping.

                         The Pseudo Baseband hopping means that synthesizers are used to provide
                         baseband-like hopping without using F-bus. The difference of pseudo BB-
                         hopping and RF-hopping is that only initial frequencies defined to the TRXs at
                         the BSC are used. The other difference is that TSL1-TSL7 of the BCCH TRX are
                         performing RF hopping. When TSL1-TSL7 at the BCCH TRX are tuned to some
                         other frequency than the BCCH frequency, one of the TCH TRXs must replace
                         the BCCH frequency broadcasting.


       BCCH timeslot, does not hop.

                 RTSL-0 RTSL-1 RTSL-2 RTSL-3 RTSL-4 RTSL-5 RTSL-6 RTSL-7


      TRX-1       BCCH      0       0      0       0      0          0      0       f1


      TRX-2         0       1       1      1       1      1          1      1       f2

      TRX-3         1       2       2      2       2      2          2      2       f3


      TRX-4         2       3       3      3       3      3          3      3       f4




   Timeslot 0 of TRXs 2-4 hop over MA(f2,f3,f4).              All timeslot 1-7 hop over MA(f1,f2,f3,f4)




                         Figure 19.     BB-hopping definition in the BSC.




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                             The figure below illustrates the frequency hopping functioning in the case of
                             pseudo BB-hopping when the hopping groups are defined as described in the
                             previous figure and cyclic hopping is used (HSN = 0 in both hopping groups).
                             The figure describes, which TRX is transmitting in which frequency at which
                             time. In this example the f1 < f2 < f3 < f4.


 TDMA frames    0                       1                       2                       3                       4
 ts             0 1   2 3 4 5 6 7 0 1         2 3 4 5 6 7 0 1         2 3 4 5 6 7 0 1         2 3 4 5 6 7 0 1         2 3 4 5 6 7
 TRX1/BCCH     B f1 f1 f1 f1 f1 f1 f1 B f2 f2 f2 f2 f2 f2 f2 B f3 f3 f3 f3 f3 f3 f3 B f4 f4 f4 f4 f4 f4 f4 B f1 f1 f1 f1 f1 f1 f1


 TRX2          f2 f2 f2 f2 f2 f2 f2 f2 f3 f3 f3 f3 f3 f3 f3 f3 f4 f4 f4 f4 f4 f4 f4 f4 f2 f1 f1 f1 f1 f1 f1 f1 f3 f2 f2 f2 f2 f2 f2 f2


 TRX3          f3 f3 f3 f3 f3 f3 f3 f3 f4 f4 f4 f4 f4 f4 f4 f4 f2 f1 f1 f1 f1 f1 f1 f1 f3 f2 f2 f2 f2 f2 f2 f2 f4 f3 f3 f3 f3 f3 f3 f3


 TRX4          f4 f4 f4 f4 f4 f4 f4 f4 f2 f1 f1 f1 f1 f1 f1 f1 f3 f2 f2 f2 f2 f2 f2 f2 f4 f3 f3 f3 f3 f3 f3 f3 f2 f4 f4 f4 f4 f4 f4 f4




                             Figure 20.         Example of changing frequencies during pseudo BB-hopping


                             The MetroSite and ConnectSite 10 TRX has CHDSP and EQDSP functionality.
                             The CHDSP and EQDSP have the same functions as the corresponding functions
                             in TalkFamily. In addition, RF hopping functionality is implemented to the
                             CHDSP part.

                             With RF hopping and with pseudo BB-hopping the CHDSP-EQDSP connections
                             are always made one-to-one. The CHDSP sends the RF channel number and DL
                             data to be used to the RF part of the TRX according to the FH sequence. The
                             synthesizers are tuned according to this information. The uplink data is coming
                             from the RF-part via EQDSP to the CHDSP.

                             The figure below describes the frequency hopping environment in the MetroSite
                             BTS.




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                                                                           BTS

                     CHDSP         FBIA        TRX           TX


                                                EQDSP        RX



                                        FBUS



                     CHDSP         FBIA        TRX           TX


                                                EQDSP        RX



                                        FBUS


                                               TRX
                     CHDSP         FBIA                      TX


                                                EQDSP        RX



                                        FBUS


                                               TRX
                     CHDSP         FBIA                      TX


                                                EQDSP        RX




               Figure 21.     MetroSite Hopping environment


               Nokia UltraSite and ConnectSite 100 implementation

               UltraSite and ConnectSite 100 BTSs support Baseband (BB) and Synthesized
               (RF) frequency hopping.




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          The default hopping mode is non-hopping. The frequency hopping mode is
          configured separately for each BTS object. Only one type of hopping mode is
          allowed in a BTS object. However, different BTS objects can have different
          hopping modes active at the same time.

          The Channel Coder Digital Signal Processor (CHDSP) and the Base Operation
          and Interface Unit (BOI) manage the frequency hopping functionality in the BTS.

          The CHDSP performs:

          .
                 · Frequency hopping calculations
          .      · Controls the RX and TX burst switching between TRXs

          The Base Operations and Interface unit manages:

          .      · Configuration messages sent from the BSC to the CHDSP
          .      · F-Bus master TRX assignment and reconfiguration
          .      · Slave TRX assignment

          CHDSPs are located in the Dual Baseband Units (BB2).

          The synthesized frequency hopping (RF-hopping) feature is adapted from the
          MetroSite BTS to the UltraSite, ConnectSite 10 and ConnectSite 100 BTSs. RF-
          hopping is available in configurations that have at least 2 TRXs per sector
          because one of the TRXs in each sector is a BCCH TRX (If MultiBCF feature is
          not used). The BCCH TRX cannot hop because the BCCH frequency must be
          continuously transmitted in a cell to enable the MS to measure BCCH-signal
          strength. This means that only non-BCCH TRXs can employ synthesized
          frequency hopping. The maximum number of frequencies available for hopping
          is 63 per hopping group.

          All RF-hopping CHDSPs are initialized with hopping groups generated by the
          BOI according to hopping information received in the BTS_CONF_DATA
          message sent from the BSC. Synthesizers in a particular TRX are tuned to
          different channels according to hopping sequence. RF-hopping is not supported
          with RTC configurations. A TRX connected to the cavity of an RTC must remain
          in the tuned channel all the time.

          The UltraSite and ConnectSite 100 baseband hopping feature is similar to the
          Talk family but with an architecture change. There is no separate FHDSP
          processor in the UltraSite and ConnectSite 100 BTS architecture like in the Talk
          family to calculate the hopping algorithm or to control the F-bus. The CHDSP
          processor is utilized in the UltraSite and ConnectSite 100 BTS architecture to
          perform these functions. Only one CHDSP in a baseband hopping sector is
          selected to perform as an F-bus master TRX. All other CHDSPs in the same




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                  UltraSite or ConnectSite 100 BTS cabinet perform as F-bus slave TRXs. F-bus
                  slave TRXs do not control the F-bus or calculate the hopping algorithm. The F-
                  bus master status can be assigned to any TRX in the baseband hopping sector but
                  within the same UltraSite or ConnectSite 100 BTS cabinet.

                  Back to Implementation principles of Frequency Hopping, functional split



3.2            BSC Implementation of Frequency Hopping
                  BSC functionality related to frequency hopping is implemented by software.
                  There are no hardware dependencies.

                  Telecom software

                  In the telecom BSC software frequency hopping is not very visible. The main
                  principle is that the BSC is handling `logical channels' of cells (the number of
                  channels varies) and in case of frequency hopping there are just some additional
                  parameters (MA, MAIO , HSN) attached to those channels when needed. The
                  parameters are offered for the use of telecom software by a database maintained
                  by O&M software.

                  Abis Interface Program Block (ABIPRB) composes Abis and Radio interface
                  (RR) messages. It reads hopping related parameters from the database.

                  Radio Resource Management Program Block (RRMPRB) does not know about
                  frequency hopping. It allocates logical channels, and hopping related parameters
                  are attached later on.

                  Radio Connection Supervision Program Block (RCSPRB) and Handover Attempt
                  Supervisor Program Block (HASPRB) have no other hopping related special
                  functions than to allow downlink power control for BCCH-TRX as well, in case
                  of a baseband hopping BTS.

                  In Abis and Radio interface (RR-level) signalling, frequency hopping is seen in
                  CHANNEL_ACTIVATION (Abis), IMMEDIATE_ASSIGNMENT (Radio),
                  ASSIGNMENT_COMMAND (Radio) and HANDOVER_COMMAND (Radio)
                  messages. In system info messages there are some hopping related parameters
                  also: the Cell Allocation bitmap (CA), the PWRC indicator and the
                  channel description of the CBCH (cell broadcast channel).




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          O&M; Configuration Management

          It is possible to manage the BSS radio network data locally in the BSC site by
          means of the local MMI, or in Nokia NetAct. The NetAct-BSC radio network
          managements communicate with each other via the Q3 interface. The
          modifications that are made in the radio network parameters stored in the BSS
          Radio Network Configuration Database with the BSC's local MMI are updated in
          NetAct.

          The BSS Radio Network Configuration Database (BSDATA) contains the
          permanent data of the BSS radio network. It provides other processes with the
          means for updating and inquiring permanent data stored in the BSC and specific
          to the radio network.

          Relations between logical radio network objects

          The overview of the partial containment hierarchy for the logical radio network
          objects stored in the BSS Radio Network Configuration Database (BSDATA) is
          presented in Figure Relations between logical radio network objects .

                                               BSC




           TRK_TBL                  BCF              BA         MA



                                    BTS




          FHS                TRX           HOC            POC        ADJC



                           RTSL



          Figure 22.     Relations between logical radio network objects.




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               In general, a higher-level object instance has to be created in the BSDATA before
               the related lower-level object can be created.

               Frequency Hopping System (FHS) object instances are created implicitly in the
               BSDATA when a BTS object instance is created by means of the MMI. Time slot
               (RTSL) object instances are also implicitly created when the related TRX object
               instance is created in the BSDATA.

               HOC, POC, FHS, and RTSL object instances cannot be independently removed
               from the BSDATA, but they are removed from the database when the related
               higher-level object instance (the BTS or TRX) is removed from the database by
               means of the MMI.

               The administrative state of the BCFs, BTSs, TRXs, and RTSLs can be defined
               independently of the administrative state of the related objects.

               O&M; Fault Management

               The BTS may send alarms which indicate that there is a fault affecting the
               hopping capabilities. The BSC then takes actions to minimise the influences of
               the fault.

               O&M; Radio Network Recovery

               The radio network configuration management determines the recovery actions of
               the BSC in abnormal situations of the BSS radio network, such as faults, fault
               cancels, and initialisations that concern the BSS subsystem. For more information
               on radio network configuration management, refer to Radio Network
               Configuration Management. The function class receives radio network recovery
               requests from the Radio Network Maintenance function class.

               The recovery actions are executed if the errors occur in the functional blocks of
               the BTS, such as the Carrier Unit (CU), the Frame Unit (FU), Transceiver (TRX),
               functional blocks common to whole BTS (cell), or the functional blocks common
               to the whole BTS site, for example the Frequency Hopping Unit (FHU). In
               addition to this, the recovery actions are executed if the D-channel of the Abis
               interface fails or if there are failures detected by the call control of the BSC in
               connection with the radio channel allocation procedure.

               The recovery actions are determined on the basis of the type of the faulty
               functional block and they are based on the radio facilities configured to the faulty
               block.

               The following actions are performed in fault cases with a hopping BTS:

               Nokia 2nd generation base stations




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          Frame Unit fault: Block the TRX. The corresponding CU and its frequency stays
          in the MA(s) for calls in the other TRXs.

          Carrier Unit fault: Block the TRX. The frequency is removed from the MA(s). All
          the calls in the cell are cut and the MA(s) and MAIOs are recalculated for the
          remaining TRX(s).

          Nokia Talk-family, PrimeSite, MetroSite, UltraSite, ConnectSite 10 and
          ConnectSite 100 Base Stations

          TRX fault: Block the TRX. In case of baseband hopping, remove the frequency
          from the MA(s) and recalculate the MA(s) and MAIOs for the remaining TRX(s).

          BCF fault: Block the BCF. If only hopping capability was lost, the cells can be
          manually changed into non-hopping mode.

          BCCH recovery is executed normally but in case of a baseband hopping BTS all
          the TRXs of the BTS, or all the TRXs of the layer if IUO is used, are blocked
          during the operation.

          Back to Implementation principles of Frequency Hopping, functional split




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4              Interaction of Frequency Hopping with
               Other Features
                 Handovers

                 When frequency hopping is used in the target cell, the handover command
                 contains the respective MA-list, MAIO , HSN, and the Cell Allocation list of the
                 target cell.

                 In intra-BTS handover cases the TCH of the best quality will be allocated
                 primarily from the other TRX than the actual one, regardless of the MS power
                 class or whether the actual TRX is a hopping one or not.

                 Intelligent Underlay Overlay, Intelligent Frequency Hopping (IFH)

                 The different interference characteristics of the regular and the super reuse layers
                 in Intelligent Underlay Overlay require that the frequency plan is constructed
                 separately for each layer. The super-reuse layer has frequency hopping
                 parameters of its own, which allow hopping separately for both layers of an IUO
                 cell. A new hopping group is introduced for that purpose.

                 The following parameters are definable separately for both layers: Hopping
                 Mode (MML parameter name UHOP ), HSN (UHSN) , MA-list (UMAL) ,
                 MAIO Offset (UMO) , MAIO Step (UMS) . It is possible to make only one of
                 the IUO layers hopping. Both baseband hopping and RF hopping modes are
                 supported, though only one mode is allowed within a BCF at a time if site type is
                 Nokia TalkFamily.

                 All the super-reuse TRXs in a cell have to belong to the same IUO frequency
                 group, because frequency hopping is performed between all the TRXs.

                 The Child Cell is a special part of the IUO concept. The hopping group
                 arrangement is somewhat different from normal IUO cells as there are only super-
                 reuse TRXs in a child cell. With BB hopping there are two hopping groups in use
                 and with RF hopping there is only one group. HSN1 and UHSN are used with a
                 BB hopping child cell and only UHSN with a RF hopping one.




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          Cell Broadcast

          The CBCH (Cell Broadcast Channel) is not hopping if it is using an SDCCH/4
          subchannel in the BCCH time slot. Otherwise (SDCCH/8 subchannel) the CBCH
          is hopping, if located in a hopping TRX. The channel description (hopping
          parameters) for the CBCH (max. 32 frequencies) is broadcast to the mobiles in a
          system information message.

          Half Rate

          If cyclic hopping (HSN = 0) is used, then the Half Rate channels use only half of
          the frequencies defined in the MA-list in the hopping sequence, thus reducing the
          benefit reached with hopping over all frequencies in an MA-list. With random
          hopping the HR channels are hopping over all frequencies defined in the MA-list
          thus getting the same profit from frequency hopping as FR channels.

          Downlink DTX

          Baseband hopping combined with downlink DTX causes problems in the mobile
          stations, because in the silent phase, dummy frames are sent on the BCCH
          frequency causing malfunction in the mobile stations. ETSI has approved a
          solution to solve the problem and it is implemented in Nokia BSS. The solution is
          to use a special training sequence code in the dummy burst, but it does not
          guarantee that all mobile station models of different manufacturers are working
          error free.

          Extended Range Cell (Nokia Talk-family of base stations)

          Only RF hopping is supported, and only for the TRXs serving the normal
          coverage area. The TRXs serving the extended coverage area cannot hop.

          MS Speed Detection

          The speed detection algorithm in the BTS works only for non-hopping channels.
          In case of frequency hopping the speed information in the Measurement Result
          message from BTS to BSC is set to the value 'non-valid' indicating that speed
          information is not available from that particular cell.

          DL Power Control

          If baseband hopping is being used in the BTS, the BSC sends the power control
          (PC) commands also to the BCCH transceiver. All bursts of one hopping group
          except the burst on the BCCH frequency are transmitted with the commanded
          power level. All bursts in the BCCH frequency are transmitted with the
          predefined BCCH power level. If frequency hopping is not being used, the BSC
          does not send the PC commands to the BTS via the BCCH transceiver. The
          sending of PC commands to the MS is not affected by frequency hopping.




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               Interference Level Measurement

               BTS performs continuous interference level measurement on each idle RTSL and
               reports the results to the BSC at regular intervals. The BSC uses the information
               when rating the channels for the channel allocation procedure. In case of a
               hopping RTSL the measurement is performed according to the actual hopping
               sequence. Thus, the result is an average over the RTSLs hopping together,
               reflecting the same perceived interference that an active channel would do.

               Radio Channel Allocation

               For interference reasons, it is sometimes reasonable to favour the BCCH TRX in
               channel allocation. On the other hand, sometimes it is better to choose a channel
               from a non-BCCH TRX. Especially when RF hopping is used in a cell, this
               matter may be important.

               TCH allocation between TRXs in one cell is managed by a BTS-level parameter
               which defines whether the BCCH TRX or the non-BCCH TRXs are preferred.

               For more information see Radio Channel Allocation.

               GPRS

               If the GPRS is in use, there can also be a PBCCH channel in the BCCH TRX ,
               which can hop using BB-hopping.

               Multi BCF and Common BCCH Control

               With Multi BCF control, the operator can combine several Base Stations into one
               logical cell. This is done by introducing the Segment object in the BSC. The
               segment may include many BTS objects from different Base Stations. The BSC
               supports Multi BCF Control for Nokia TalkFamily, Nokia UltraSite, Nokia
               MetroSite, Nokia ConnectSite 10 and Nokia ConnectSite 100 base stations.

               The basic idea behind the Common BCCH Control is to include resources from
               different frequency bands into one cell by letting them share a common BCCH
               that has been allocated from one frequency band used in the cell.

               Frequency hopping is BTS specific even if the MultiBCF Control feature is in
               use.

               Internal Description of Frequency Hopping

               Frequency Hopping Implementation Description

               Implementation principles of Frequency Hopping, functional split




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